Installing exterior wall vent cap for bath exhaust fan

Hi there, I have a question regarding vent cap install on exterior wood siding as seen in the picture. The 6" vent cap is for a new bathroom exhaust fan and made of galvinized steel. The problem is there is no holes round edge of the cap so I can't use screws to secure it onto the wall siding. Is caulking along enough? if is what type of caulk or adhesive would be good for this. Should I nail through the metal flashing to secure it? Thanks.

Installing exterior wall vent cap for bath exhaust fan

Installing exterior wall vent cap for bath exhaust fan

Joecaption, thanks for your reply. My questions are about the choice of caulk or adhesives, and how to secure the vent cap without predrilled screw holes. I haven't seen any vent caps with siding block so I would not try that. The picture is from internet and not me, but the install and type of cap are similar.

Installing exterior wall vent cap for bath exhaust fan

Drill your own hole in the flange. Caulk is not enough.

You don't need to use a siding block but you have to make sure you have a good seal around the bottom or wind driven rain will get in. The siding block will make it look better and make aligning the duct work easier. When you mount it directly to the siding, the duct connection is angled downwards.

Installing exterior wall vent cap for bath exhaust fan

Dan, thanks for the advice. I will predrilled holes and screw it on. My siding is T11 type and a little different than that in the picture. In my case the cap will be attached to the wall flat so I am ok without siding block. Thanks again. Ray